To thrive in an ever-changing environment, microbes must widely distribute their progeny to colonize new territory. Simultaneously, they must evolve and adapt to the stresses of unpredictable surroundings. In both of these regards, diversity is key—if an entire population moved together or responded to the environment in the same way, it could easily go extinct. Here, we show that the epigenetic prion switch [SWI⁺] establishes a specialized subpopulation with a “pioneer” phenotypic program in Saccharomyces cerevisiae. Cells in the pioneer state readily disperse in water, enabling them to migrate and colonize new territory. Pioneers are also more likely to find and mate with genetically diverse partners, as inhibited mating-type switching causes mother cells to shun their own daughters. In the nonprion [swi⁻] state, cells instead have a “settler” phenotype, forming protective flocs and tending to remain in their current position. Settler cells are better able to withstand harsh conditions like drought and alkaline pH. We propose that these laboratory observations reveal a strategy employed in the wild to rapidly diversify and grant distinct, useful roles to cellular subpopulations that benefit the population as a whole.

为了在瞬息万变的环境中蓬勃发展，微生物必须广泛分布其后代，以定居新的领土。同时，它们必须进化并适应不可预测的环境压力。在这两个方面，多样性都是关键-如果整个人口一起迁移或以相同的方式对环境做出反应，它很可能会灭绝。在这里，我们表明表观病毒开关[ SWI ⁺ ]在酿酒酵母中建立了具有“先锋”表型程序的专门亚群。处于先驱状态的细胞可以很容易地分散在水中，从而使其能够迁移并定居在新的领域。拓荒者也更有可能找到具有遗传多样性的伴侣并与之交配，因为受抑制的交配方式转换会导致母细胞避开自己的女儿。在nonprion [ SWI ^- ]状态，而不是细胞具有“沉降”表型，在形成保护性絮凝物并倾向于留在其当前位置。定居者细胞更能承受恶劣条件，例如干旱和碱性pH。我们建议这些实验室观察揭示了一种在野外采用的策略，以迅速多样化并赋予有益于整个人口的细胞亚群独特，有用的作用。